This invention relates to a system for removing carbon dioxide (CO2) from an air stream and specifically to a metal encapsulated sorbent sheet allowing diffusion of gases for removing CO2.
Currently systems for controlling and removing CO2 from a breathable air supply are utilized in submarines, space vehicles and space suits. These systems pass an air stream through a CO2 sorbent CO2 within the air stream reacts with the sorbent and is trapped. The remainder of the breathable air recirculates into the controlled environment. Once the container has become saturated with CO2 such that further absorption of CO2 is inefficient, the breathable air stream is switched to a second container. The saturated container is either disposed of or regenerated.
Systems that use flat sheet sorbents offer advantages over traditionally packed bed sorbent configurations. These advantages include higher packing densities with lower pressure drops and the potential for flow-by configurations where it is desired to allow air free flow pass the sorbent. Free flow configurations minimize direct contact of the flow stream with the sorbent and reduce entrapment of particles within the sorbent.
Flat sheet sorbents may be regenerable and non-regenerable and are typically encapsulated within a non-metallic material such as a porous fluorinated or non-fluorinated polymeric membrane. Encapsulation of sorbents within a polymeric membrane is costly to manufacture and difficult to handle due to the fragile nature of such construction. The flexibility and fragile nature of the sorbent sheets, in addition to a tendency to expand upon reacting with CO2, require that additional structural elements be included in the overall assembly to prevent damage. The additional structural elements add cost and increase the overall size of the sorbent assembly.
Further, the non-metallic material tends to expand under the heat typically generated during absorption of CO2. As appreciated, airflow passages disposed within the CO2 sorbent sheet are specifically tailored to provide a specific pressure drop tailored to a specific system. Expansion and contraction of the CO2 sorbent may in turn cause undesirable variation of system parameters.
Accordingly, it is desirable to develop a CO2 sorbent sheet that is structurally rigid and is dimensional stable during operation.
A disclosed embodiment of this invention is a CO2 sorbent sheet encapsulated within a metal material of a porous nature for allowing diffusion of gases from an adjacent flow stream.
The sorbent sheet is encapsulated within a porous metal material having material properties tailored to specific applications to provide the desired absorption by the CO2 system. The sorbent sheet is encapsulated within a porous metal material and allows the absorption of specific quantities of CO2 and water from a flow stream, and prevents extrusion of the sorbent.
In another embodiment of this invention, the metal material includes a plurality of openings to form a fine mesh that allows the diffusion of gases into the sorbent material from an adjacent flow stream.
Further, the CO2 sorbent sheet of this invention includes integrally formed air passages that are dimensioned relative to the desired pressure drop and configuration of the system. The integrally formed air passages cooperate with other sorbent sheets assembled within the system to provide the specific dimensions for airflow through the system. The sorbent sheets include support rods that extend the entire length of the sorbent sheet and are integrally formed within the sorbent sheet. Further, in one embodiment of this invention, the air passages are integrally formed along one side of the CO2 sorbent sheet and cooperate with other sheets disposed within a housing to form airflow passages that provide a specifically desired pressure, drop through the system.
Accordingly, the system and assembly of this invention provides a durable and cost effective sorbent sheet that reduces manufacturing costs by reducing the number of parts required and increases the durability and survivability of each sorbent sheet assembly.